Thursday, December 02, 2010

Global Health and Wealth over Two Centuries

Here is a story in four minutes of remarkable divergence followed by rapid convergence in health and wealth across nations over the past two centuries (h/t David Kurtz)

Where the entire world was clustered in 1810 only sub-Saharan Africa remains. But even here there are profound stirrings of change.

I suspect that someday soon animations such as this will replace the soporific tables and charts than now appear as motivating evidence in economic papers.

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Update (12/6). Pinkovskiy and Sala-i-Martin argue that over the past decade and a half, the nations of sub-Saharan Africa have experienced a dramatic and broad-based decline in poverty and inequality (h/t Mark Thoma):

African poverty reduction has been extremely general. Poverty fell for both landlocked and coastal countries, for mineral-rich and mineral-poor countries, for countries with favourable and unfavourable agriculture, for countries with different colonisers, and for countries with varying degrees of exposure to the African slave trade. The benefits of growth were so widely distributed that African inequality actually fell substantially...

It has often been suggested that geography and history matter significantly for the ability of Third World, and especially African, countries to grow and reduce poverty... Since these factors are permanent (and cannot be changed with good policy), they imply that some parts of Africa may be at a persistent growth disadvantage relative to others.

Yet... the African poverty decline has taken place ubiquitously, in countries that were slighted as well as in those that were favoured by geography and history. For every breakdown... the poverty rates for countries on either side of the breakdown tend to converge, with the disadvantaged countries reducing poverty significantly to catch up to the advantaged ones. Neither geographical nor historical disadvantages seem to be insurmountable obstacles to poverty reduction... even the most blighted parts of the poorest continent can set themselves firmly on the trend of limiting and even eradicating poverty within the space of a decade.

I have argued in a couple of earlierposts that sub-Saharan Africa may have entered what might be called a zone of uncertainty in which optimistic growth expectations can become self-fulfilling:

History can matter for long periods of time (for instance in occupational inheritance or the patrilineal descent of surnames) and then cease to constrain our choices in any significant way. Once reliable correlations can break down suddenly and completely; history is full of such twists and turns. As far as African prosperity is concerned, I believe that a discontinuity of this kind is inevitable if not imminent.

11 comments:

Yes, it's amazing how efficiently the information is packed into such a small amount of space and time. This kind of thing can easily be embedded in a pdf file though I've never seen a paper that does it.

Nick, I'm not sure why we can absorb huge amounts of information in some formats but not others, though I'm sure that evolutionary psychologists have a few ideas. But whatever the reason, there are some interesting implications. For example, there's a large literature (following Crawford and Sobel) on strategic information transmission, but nothing as far as I know on strategic information presentation. If presentation in persuasive formats is costly, then the choice of format by the sender should be informative to the receiver, perhaps to the point where highly persuasive formats are treated with some suspicion?

Dynamic graphics are great, but a lot can be done with static graphs too. One advantage of static graphs is that you can arrange a grid of them on a page and look at a lot of patterns at once.

I agree with you on the "soporific tables" but not so much on your implicit dismissal of "charts" as well.

To put it another way: In econ papers, graphs are typically not a serious part of the argument. Sometimes you see a graph of raw data but then it's the model (and associated tables) that are the main story. I think it would be better if graphics were better incorporated into the modeling.

It may not be "graphs vs. models", but conflict is so much sexier than co-operation. It also makes for much cooler headlines. Don't you think "Freakonomics" (the headline) is much cooler than "Worthwhile Canadian Initiative."?

Andrew, your point about static graphs is well taken, I shouldn't have suggested that dynamic graphs are always better.

Regarding your broader point, it's true that visuals have not been a serious part of the argument in theoretical economics, since the focus has been on analytically tractable models for which theorems can be proved. I have argued in an earlier post that we should be doing more agent-based modeling, and here dynamic graphs can and should be an integral part of the argument.

Marcel, perhaps I'm in a small minority but I actually like the title "Worthwhile Canadian Initiative" in a so-uncool-it's-cool sort of way, while I find "Freakonomics" terribly off-putting and not in the least bit cool...